Problem with Victron 12v 30A DC-DC on a Peugeot Boxer with smart alternator

[RGIvy]

Hoping someone can help here, perhaps having had the same issue with the same or similar vehicle.

We installed a Victron 12v 30A DC-DC non-isolated charger into a motorhome built on a 2022 Peugeot Boxer with smart alternator.
We’ve installed many DC-DC chargers, quite a few on vehicles with smart alternators. In some cases we have had to tweak things but always got it working.
In this particular case the DC-DC charger seems to not like the base vehicle at all.
Before we give up on this particular base vehicle and charger combination just checking to see if someone faced this issue and found a solution.

The Problem - Low Input Voltage causes lock-out
After starting the vehicle the input voltage builds up in the usual way and the charger kicks in with around 30A (usually max 13v).
After a short time of running the charger detects a low input voltage, sometimes right down to 7v.
Then the input voltage lock-out kicks in and the charger stops charging (as expected).
The input voltage comes back up and the process is repeated again and again.
The charger is working at around half the time.

The Setup
Victron 12v-12v 30A DC-DC non-isolated charger
460AH 12v LiFePO4 battery
16mm² (5awg) cables used throughout
Pos 1.2m (4ft) from starter battery pos terminal to the DC-DC.
Pos 0.6m (2ft) from DC-DC to the LiFePO4 battery.
Neg 1m (3ft) from DC-DC to the chassis (good solid connection) and LiFePO4 battery
D+ cable connected to the green terminal block on DC-DC (Right “H” connector)

We’ve tried
With and without using “Engine shutdown detection” (don’t really need it because we have D+).
When using Engine shutdown detection we’ve tried default (smart alternator) plus a whole bunch of variations
Lowered the input voltage lockout right down to 12v with 12.5v reset
Different 30A charger (same model) just in case of fault (same result)
Lower amp 18A Victron DC-DC charger (same result)
Different cables (same result)

 

[justinm001]

Is your starter battery voltage actually going down to 7v?

 

[RGIvy]

Is your starter battery voltage actually going down to 7v?

No, it's dipping down but not as low as that.
It looks as if the voltage drop is over the 1.2m cable to the DC-DC, but 16mm should be more than ample and we've done loads of other installs using 16mm cable without problem.

 

[justinm001]

No, it's dipping down but not as low as that.
It looks as if the voltage drop is over the 1.2m cable to the DC-DC, but 16mm should be more than ample and we've done loads of other installs using 16mm cable without problem.

how low, below 13V? I'm not sure about smart alternators but with a normal alternator your starter battery should always be above 13v while on and if its below 13v then its pulling from the battery. If the battery is dropping below 12V then it can't handle the load. The voltage will always be lowest at the source of the load.

It sounds like you're overloading your alternator and battery with that 30amps. You didn't mention if this is happening when its driving or just idling. Alternators provide a LOT less power at low rpm, and I'd suspect this is even more so with a smart alternator. Crank the idle up to 2000 rpm or so and see what happens. see how the battery voltage is with the dash gauge and if no gauge then use a voltmeter at the battery terminal

 

[mikefitz]

Victron 12v 30A DC-DC non-isolated charger into a motorhome built on a 2022 Peugeot Boxer

The negative feed from the vehicle starter must be from vehicle metal not the negative terminal of the starter battery. It seems you have this connection.

D+ cable connected to the green terminal block on DC-DC

Where are you getting this D+? the converters outlet in the B pillar?
Where are you connecting the positive at the starter battery? The fuse array can have intermittent issues.
What fuse or breaker in the positive feed?
Have you checked the starter battery voltage variations without the unit connected ? 7 volts is hard to beleive at the battery terminal.

Normally you don't need D+ and get a usable system by adjusting the cut in/out voltages.

With the Ducato, Relay, Boxer I usually take the Orion positive from the converters fuse, the 50 A on the left in the picture.

To conform there is no fault with the alternator, smart charge control , or starter battery , or feed cables, is it possible to simulate a 40 amp DC load on the cables ? ( example, 12v inverter with a 400 watt AC load)

Have you considered that the lithium battery is entering protection and shutting down the charge path ?
What absorbtion volts are set in the Orion and what is the battery SOC?

Mike

 

[RGIvy]

Is your starter battery voltage actually going down to 7v?

Not as low as that. It is dropping but not so much.
We’ve connected a 2nd cable just in case the cable was too thin, connected to different bolt on + terminal, still same.

 

[RGIvy]

how low, below 13V? I'm not sure about smart alternators but with a normal alternator your starter battery should always be above 13v while on and if its below 13v then its pulling from the battery. If the battery is dropping below 12V then it can't handle the load. The voltage will always be lowest at the source of the load.

It sounds like you're overloading your alternator and battery with that 30amps. You didn't mention if this is happening when its driving or just idling. Alternators provide a LOT less power at low rpm, and I'd suspect this is even more so with a smart alternator. Crank the idle up to 2000 rpm or so and see what happens. see how the battery voltage is with the dash gauge and if no gauge then use a voltmeter at the battery terminal

We’ve revved the motor to around 2000RPM - no difference. We realise it could be that particular vehicle or a weak alternator, hence why we tried the 10A DC-DC (exact same result).

 

[RGIvy]

The negative feed from the vehicle starter must be from vehicle metal not the negative terminal of the starter battery. It seems you have this connection.

Where are you getting this D+? the converters outlet in the B pillar?
Where are you connecting the positive at the starter battery? The fuse array can have intermittent issues.
What fuse or breaker in the positive feed?View attachment 186418
Have you checked the starter battery voltage variations without the unit connected ? 7 volts is hard to beleive at the battery terminal.

Normally you don't need D+ and get a usable system by adjusting the cut in/out voltages.

With the Ducato, Relay, Boxer I usually take the Orion positive from the converters fuse, the 50 A on the left in the picture.

To conform there is no fault with the alternator, smart charge control , or starter battery , or feed cables, is it possible to simulate a 40 amp DC load on the cables ? ( example, 12v inverter with a 400 watt AC load)

Have you considered that the lithium battery is entering protection and shutting down the charge path ?
What absorbtion volts are set in the Orion and what is the battery SOC?

Mike

The negative is off a cable going direct to chassis (not the starter battery terminal).
As it’s a motorhome the D+ comes from the EBL. It‘s working fine.
We‘ve connected positive to various places, piggy-backing on existing fuses and also directly from the unused 8mm bolt. Tried another cable too.
The starter battery doesn’t drop as low as 7v, goes down to 12v. So a big loss over the cable. Hence why we tried another cable. We’ve never had such voltage drop on a short 16mm cable (installed many DC-DC chargers with 16mm cable). Bear in mind we tried an 18A DC-DC charger too. Very strange results.
We have installed several DC-DC on smart alternators without D+, but we find D+ to be far more stable. Especially if you need to install a cut-off or changeover relay for the existing split-charge system.
Good idea to simulate a 40A load.
The battery is not the problem, we did make sure of that. It has been charged up to full SOC a few times, and the DC-DC has been tested at various SOC to see if there is a common pattern. The vehicle has a Multiplus so when on EHU the charge rate is fast (without problem).
We‘ve tried various absorption and float settings. No change in behaviour.

 

[mikefitz]

the D+ comes from the EBL

Thus may not be a true D+, alternator charging, but derived from voltage levels on the starter battery.
Before you added the Orion I guess there was some method of charging the house battery from the starter battery/ alternator. Has this path been disabled?
It still sounds like volt drops in either the positive or negative path to the Orion.